London: The HIV pandemic began its global spread from Kinshasa, the capital of the Democratic Republic of the Congo (DRC), says a study.
Between the 1920s and 1950s, a 'perfect storm' of factors, including urban growth, strong railway links during Belgian colonial rule, and changes to the sex trade, combined to see HIV emerge from Kinshasa and spread across the globe.
"It seems a combination of factors in Kinshasa in the early 20th Century created a 'perfect storm' for the emergence of HIV, leading to a generalised epidemic with unstoppable momentum that unrolled across sub-Saharan Africa," said senior study author Oliver Pybus, a professor at Oxford University in Britain.
For the study, the researchers reconstructed the genetic history of the HIV-1 group M pandemic, the event that saw HIV spread across the African continent and around the world.
"For the first time we have analysed all the available evidence using the latest phylogeographic techniques, which enable us to statistically estimate where a virus comes from," Pybus said.
"This means we can say with a high degree of certainty where and when the HIV pandemic originated," Pybus added.
HIV is known to have been transmitted from primates and apes to humans at least 13 times but only one of these transmission events has led to a human pandemic.
It was only with the event that led to HIV-1 group M that a pandemic occurred, resulting in almost 75 million infections to date.
"We think it is likely that the social changes around the independence in 1960s saw the virus 'break out' from small groups of infected people to infect the wider population and eventually the world," first author of the study, Nuno Faria from Oxford University said.
The study appeared in the journal Science.